In the past various different methods were employed to treat a core of a dynamoelectric machine with a hardenable liquid adhesive material in order to bond together the interfacing lamination surfaces of the core. A typical past core had a lamination stack, and the laminations may have been retained in interfacing relation in the stack by suitable means, such as welding, bonding or cleating or the like for instance. Winding means associated with the stator included a plurality of coils having opposite side turn portions received in slots provided therefor in the core, and the coils also had opposite end turn portions arranged in generally annular groupings thereof adjacent the opposite end faces of the core. Of course, suitable insulation, such as for instance a slot liner of dielectric material, was provided in the core slots to electrically insulate the opposite side turn portions of the coils from the core, and suitable winding retaining means, such as slot wedges or the like for instance, were positioned in the slots of the core to maintain the opposite side turn portions of the coils against displacement from the slots into the bore of the core.
In one of the aforementioned past treatment methods for the core when the laminations were retained by welding or cleating, the core and its winding means were baked or preheated to a preselected temperature, and while at such an elevated temperature, the core and its winding means were immersed or dipped into a bath of the liquid adhesive material. When the core was so immersed, it is believed that the liquid adhesive material entered into the core for the most part from the outer circumferential portion of the core and penetrated by capillary action between the interfacing lamination surfaces of the core. When later removed from the liquid adhesive material bath, the core and its winding means were rebaked or reheated to effect the hardening or curing of the liquid adhesive material which had adhered to the core. In some instances, the core and its winding means may have been reimmersed in the liquid adhesive material bath and rebaked. While the above discussed past treatment method may have bonded together the laminations of the core to provide adequate core strength, one of the disadvantageous or undesirable features of such past treatment method is believed to be that it may have been necessary to wipe excess liquid adhesive material from the opposite end faces and the circumferential surface of the core prior to baking the core to cure the liquid adhesive material.
Still another past method of treating a loose wound core involved a bolt-down bonding process as shown in U.S. Pat. No. 3,821,846 issued July 2, 1974 to Bernard J. Pleiss, Jr. In this past method, a plurality of bolts were extended through bolt holes provided in the loose lamination stack of the loose wound core so as to mount an opposite end face of the loose wound core against a bolt down fixture. Upon torquing of the bolts, the interfacing lamination surfaces in the loose lamination stack were forced or clamped together by the bolts generally in the vicinity of the bolt holes thereby to establish generally axial compression regions generally adjacent the bolt holes between the opposite end faces of the loose wound core. When so mounted to the bolt-down fixture, the loose wound core was preheated and immersed into a liquid adhesive material bath with the exception of the annular end turn grouping of the windings adjacent the winding lead ends. Since the bore of the loose wound core was mounted on an alignment mandrel, it is believed for the most part that the liquid adhesive material may have penetrated by capillary action from the outer circumferential surface of the loose wound core between the interfacing lamination surfaces thereof except for the axial compression regions established adjacent the bolt holes. Albeit not discussed or even suggested in the Pleiss, Jr. patent, it is believed that the possibility may have existed wherein some of the liquid adhesive material may have been transferred in some manner from the slots of the loose wound core by capillary action between the interfacing lamination surfaces of the loose wound core. Thereafter, the loose wound core was baked to effect the curing of the liquid adhesive material in the loose wound core thereby to bond it together. Nevertheless, it is believed that this past treatment method for loose wound cores has at least generally the same disadvantageous or undesirable features of the previously discussed past treatment method.
As disclosed in U.S. Pat. No. 4,559,698 issued Dec. 24, 1985 to Eugene C. Bair et al., liquid adhesive material was applied or metered onto annular end turn groupings of winding means of a core, and in response to a preselected rotation sequence of the core, the liquid adhesive material was flowed from the end turn groupings along opposite side turn portions of the winding means into slots of the core within insulating slot liners and slot wedges in the core slots. Since the slot liners and slot wedges in part overlaid each other within the core slots, the liquid adhesive material was flowed between the overlaying parts of the slot liners and slot wedges into communication with interfacing lamination surfaces in the core intersecting with the core slots. By capillary action, the liquid adhesive material penetrated into the core between the interfacing lamination surfaces, and in response to subsequent baking of the core, the liquid adhesive material was cured thereby to bond the core and its winding means into a unitary mass. While this past treatment method undoubtedly exhibited many salient features, it is believed that when the necessary amount of liquid adhesive material was applied to insure proper distribution of the liquid adhesive material between the interfacing lamination surfaces to effect adequate core bond strength, some of the liquid adhesive material may have flowed from some of the core slots onto the opposite end faces of the core. Of course, prior to baking of the core, it was necessary to wipe away any liquid adhesive material which may have accumulated on the opposite end faces of the core, and as previously mentioned, it is believed that the additional operation of removing the liquid adhesive material from the opposite end faces of the core may have been a disadvantageous or undesirable feature of this past treatment method.
In West German Patent No. 2,826,260, liquid adhesive material was flowed through a plurality of apertures in a slot liner in each core slot so as to adhere the slot liner in the slot. The West German Patent alleges that the adherence of the slot liners in the slots obviates displacement of the slot liners and windings contained therein in response to vibration which may occur when the windings are energized and also that such apertures facilitate cooling of the windings. However, one of the disadvantageous or undesirable features of this past treatment method is believed to be that the voltage creepage distance through the apertures in the slot liners between the windings within the slot liners and the core slots would not meet requirements of at least some national regulatory agencies, such as for instance NEMA or Underwriters Laboratories, Inc. in the U.S.A. and Canadian Standards Association in Canada.